For centuries, legend has suggested that fermented dairy products containing live active cultures (which are naturally occurring within the intestinal tract) are beneficial. According to USProbiotics.org, recent scientific investigation supports these views, suggesting that these live microorganisms—in most cases, bacteria—are a valuable part of a healthy diet.

Probiotics are available in a variety of foods and dietary supplements. Examples of foods containing small amounts of probiotics are yogurt, fermented and unfermented milk, miso, tempeh, and some juices and soy beverages. As the trend toward healthier living continues, companies are beginning to market their products as containing probiotics, including Dannon’s Activia yogurt and Kraft’s LiveActive cheese. Even some breakfast cereal labels now boast added probiotics.

“The food sources for probiotics may not be enough if you have digestive issues,” Bonaventure says. “But for maintenance, they can do the trick.”

“In order to get a benefit from the yogurt, you would have to eat gallons of it,” she says. “Yogurt and other dairy products are acidic and can counteract the effectiveness of a probiotic. Instead, we recommend a high-quality probiotic supplement. The liquid versions or softgels with powder inside are very easy for the body to absorb.”

So what are probiotics used for? In many circumstances, people use them to prevent unwanted side effects caused by antibiotics.

“When you take an antibiotic, it doesn’t differentiate between your body’s good and bad bacteria—it kills it all,” Bonaventure says. “When you stop taking your antibiotic, there’s a chance the ‘bad’ bacteria can take over, disrupting your body’s digestive system. By adding a probiotic to your diet, you can help your body maintain a healthy balance between the good and bad bacteria.”

“People who lack beneficial flora frequently suffer with yeast infections, urinary tract infections, skin problems, fatigue, jock itch, irritable bowel syndrome, belching, diarrhea, heartburn, and other problems,” says Cohen. “People tend to get used to these symptoms and chalk them up to eating habits or bad genetics, so I emphasize the importance of probiotics. Stress, illness, junk food, sugary foods, alcohol, and coffee also tilt your gut in the wrong direction.”

Cohen adds that probiotics are an inexpensive, easy way to build up your immune system.

In fact, as research on the topic grows, it’s suggested that probiotics have the potential to help with a variety of ailments, including lactose intolerance, Crohn’s disease, and irritable bowel syndrome. Preliminary research is also delving into whether or not certain probiotic strains can help reduce the occurrence of some cancers, and if they can assist with reducing recurring kidney stones.

Of course, Bonaventure warns that patients shouldn’t view probiotics as a medical treatment.

“If there is a serious condition, it’s best to see your doctor,” he says. “Probiotics, though, can help your gut function better, allowing the rest of your body to follow suit.”

Perhaps one of the greatest benefits of probiotics is that they can help keep healthy people healthy by supporting and enhancing immune function. Remember, many of your body’s health woes originate in the gut.

Lemier points out that in our culture, we tend to focus on the symptoms themselves rather than the cause of those symptoms.

“The source of so many of our health problems is our poor diet,” Lemier says. “We need to change the way we eat and what we eat if we want to improve our overall health. Often, we chase the symptoms we’re feeling rather than the cause of our problem.”

“The friendly bacteria normally found within the intestinal tract serves many purposes,” Bonaventure adds. “Once the probiotic reaches your intestine, it begins growing and replicating, helping to create the mucosal lining that acts as a barrier for food and viruses that pass through the intestines. The probiotic also produces enzymes that aid in digestion.”

The normal human digestive tract contains about 400 types of probiotic bacteria. The largest group is lactic acid bacteria, of which Lactobacillus acidophilus, found in yogurt, is the best known. Some people though, for a variety of reasons including illness, stress, and poor diet, don’t have the proper immune function to maintain a healthy level of beneficial bacteria.

“These are the people who could benefit most from a probiotic,” Bonaventure says. “If you have a healthy bowel system, you don’t need to take it daily. Unfortunately, not many of us have a healthy system because of the processed foods and sugars we eat, caffeine, emotional and physical stress, and illness. All of these things take away our body’s natural ability to fight illness.

“I take a probiotic myself and I notice a positive change in my body,” he adds. “I believe the body has an incredible power to heal a lot of our problems if it’s given the right tools and nutrients.”

Bonaventure describes complementary medicines as “smorgasbords” for the body.

“When you take a multi-vitamin or supplement, it’s like you’re laying these nutrients out for your body to cherry-pick from,” he says. “Each day, hour, or minute, your body may choose different nutrients based on physical activity, exposure to viruses, and stress.”